New pyrazole derivative as effective corrosion inhibitor for carbon steel in 1 M HCl: Experimental and theoretical analysis

Abstract

Corrosion inhibition is an extensive field of study, and its progression is gaining traction among researchers. This paper describes a study to synthesize and characterize a novel class of organic corrosion inhibitor called (3, 5-dimethyl-1H-pyrazol-1-yl) (4-((4-chlorobenzy-lidene) amino) phenyl) methanone) (DPCM). The structure of DPCM was determined using FTIR, 1H NMR and 13C NMR techniques. The effectiveness of DPCM was tested on carbon steel in 1 M HCl using electrochemical and weight loss methods, and it was found that the inhibition efficiency increased with increasing temperature and DPCM concentration. The highest inhibition efficiency of 89.5% was achieved at 60 °C and 400 ppm DPCM. The inhibition action of DPCM molecules was achieved by blocking the metal surface by means of the adsorption of inhibitor molecules obeying the Langmuir adsorption isotherm. Adsorption-free energy indicates a spontaneous chemical adsorption process. The polarization test results clarified a mixed effect of DPCM on anodic and cathodic reactions. Electrochemical impedance spectroscopy indicated an increase in metal resistance in the presence of an inhibitor. The formation of a protective layer was confirmed by SEM and AFM analysis. Density functional theory (DFT) simulation has been used to determine the relationship between molecular configuration and their inhibition efficiencies.